The present invention relates in general to plastic closures or caps for bottles and other containers formed with a retaining external bead at the outer end of their neck. More particularly, this invention is directed to provide a plastic closure of this general type, which comprises an outer skirted closure cap adapted to be assembled either during the closure manufacturing process or at the time of actual use with an inner or main closure cap forming with said outer cap a double walled space adapted to receive a product.
The chief difficulty to be overcome in devices of this type lies in the means used for securing the outer skirted cap to the inner cap constituting the stopper proper so that the dual feature of a faultless assembling and the absence of any relative movement between these elements be obtained while warranting and preserving a constant fluidtightness, especially with gaseous products. Another difficulty resides in the fact that the relative fastening of these elements must be reversible so that the inner cap can be removed from the outer cap, for example when it is desired to release the product contained in said double wall.
This fluid-tight closure consisting of two elements adapted to be firmly assembled and reversible at will comprises a main, inner cup-shaped closure cap formed with an integral peripheral flange, and an outer cap formed with an external skirt co-acting with the side wall of said main cap to provide an annular space adapted, when fitting the closure with a moderate forcing, to receive the neck of a container until the edge of said neck abutes a peripheral rib formed on the inner surface of said skirt and somewhat spaced from the bottom of said outer cap.
The external skirt of the outer cap of the two-piece closure according to this invention may comprise as already known per se a downward extension from which it is separated by at an incipient tearing or breaking line, said extension constituting a guarantee strip formed wth an integral tear-off lug, whereby the closure constitutes a definitely temper-proof device.